Grate coolers



March 1967 G. H. FORSYTH ETAL 39 GRATE COOLERS Filed March 30, 1964 3 Sheets-Sheet l :FHPHHHH 9 5 fHHHHHH March 21, 1967 e, H. FORSYTH ETAL fififl fi GRATE COOLERS 3 Sheets-Sheet 2 Filed March 50, 1964 March 21, 1967 G. H. FORSYTH ETAL. 3939,???

GRATE COOLERS Filed March 30, 1964 3 Sheets-3heet 3 United States Patent Office 33%,787 Fatented Pi lar. 21, 1967 3,349,787 GRATE COOLERS George Howard Forsyth, Joseph Hendrick Taylor, and

Andrew Campbell Grant, Lancashire, England, assignors to Vickers-Arrnstrongs (Engineers) Limited, London, England, a British company Filed Miar. 30, 1964, Ser. No. 355,745 Claims priority, application Great Britain, Apr. 3, 1963, 13,287/63 Claims. (Cl. 34-185) This invention relates to heat exchangers.

According to the present invention there is provided a heat exchanger having a rotatable grate for supporing material in a granular or nodular form, and a scraper arranged above the grate for removing from the grate material supported by the grate, the arrangement being such that in use material is deposited on the rotating grate and gases are passed through the grate and the material whereby heat exchange occurs between the material and the gases while the material supported by the grate is being carried to the scraper by the rotating grate.

For a better understanding of the invention and to show how the same may be carried into efiect reference will now be made, by way of example, to the accompanying drawings, in which:

FIGURE 1 is a vertical cross section of a neat exchanger,

FIGURE 2 is a section on the line II-II of FIG- URE 1,

FIGURE 3 is a section on the line IIIIII of FIG- URE 1,

FIGURE 4 is a vertical section taken on the line IV IV of FIGURE 2,

FIGURE 5 is a section taken on the line V-V of FIGURE 2,

FIGURE 6 is a view similar to FIGURE 1 of a modified version of the heat exchanger,

FIGURE 7 is a section taken on the line VII-VII of FIGURE 6,

FIGURE 8 is a section taken on the line VIIIVIII of FIGURE 6, and

FIGURE 9 is a section taken on the line IXIX of FIGURE 7.

The heat exchanger illustrated is intended for securing heat exchange between hot cement clinker and cooling gases and includes a rotatable annular grate 1 composed of inner and outer rings of firebars 4 and 5 which are supported by inner and outer drums 2 and 3 respectively, and on a rib 42. Secured to the drum} externally thereof is a supporting and driving member 6, the memher 6 including on the under surface thereof a toothed gear ring 7 and a roller track 8. The gear ring 7 and the track 8 are best seen in FIGURE 5. The teeth of the ring 7 mesh with the teeth of the gear wheel 9 (FIGURE 5) which is driven by a motor 10 via gearing 11 and a flexible coupling 12. A number of rollers 13 (FIGURE 1) are rotatably supported in journals 14 (see also FIGURE 2) and co-operate with the track 8 to support the grated at equally spaced intervals around the circumference of the grate 1. The inner and outer drums 2 and 3 are connected to one another by a series of radial baffles 15 which divide the space beneath the grate 1 into a plurality of sections 16. Each section 16 is connector by Way of an aperture 17 in the outer drum 3 to an annular chamber 18 formed between the outer drum 3 and an outer casing 19 of the exchanger. The casing 19 supports the journals 14.

A bathe (not shown) is arranged at a location which is approximately diametrically opposed to the duct 23 and which serves to minimise gas flow circumferentially of the grate above the grate. Further oircumferentially spaced balfies may be provided for the same purpose if desired.

The rotatable grate 1 and the parts secured thereto are disposed within an annular space formed between the casing 19 and an inner casing 29. Above the level of the firebars 4 and 5 the casings l9 and 20 are lined with fire resistant bricks 21 and the bricks 21 are themselves protected from mechanical damage by wear plates 22. The wear plates 22 terminate at a level which is just above the upper surface of the bars 4 and 5.

A firebrick lined, vertical shaft 23 forms an inlet duct for the hot clinker and an exhaust duct for gases. The upper part of duct 23 is connected to a rotary kiln (not shown). The overhanging part of the duct 23 (FIG- URE 1) is supported by columns 23A.

A fixed scraper 24 (see FIGURE 4) is sandwiched between the wear plates 22 and the firebrick wall 25 (FIGURE 2). The lower edge of the scraper 24 is above the upper surface of the grate 1. By way of example, there may be an inch between the upper surface of the firebars 4 and 5 and the lower surface of the scraper 24. The scraper 24 extends outwardly beyond the drum 3, there being a chute 26 (FIGURE 4) outside the drum 4 and beneath the blade 24. The chute 26 slopes downwardly from the blade 24 towards a screen 27. A rotary hammer or breaker 28 is mounted above the screen 27 and serves to throw large pieces of cement clinker upwardly against impact plate 29 to break these large pieces of clinker. Hanging chains 30 limit the distance to which the hammer 28 can throw the clinker. Beneath the screen 27 there is a clinker discharge opening 31 which leads to a conveyor (not shown).

The grate 1 also carries scrapers 32, the scrapers 32 being so arranged beneath the grate 1 that they reach almost to the surface of the foundation 33 of the exchanger. As will be seen from FIGURE 3, each scraper 32 includes two members arranged at an angle to one another, the region at which the two members are joined together being at the same distance from the axis of the exchanger as an opening 34 provided in the foundation 33 and which communicates with the opening 31. A grid 35 covers the opening 34 to prevent pieces of broken firebar entering the opening 34.

Two circumferentially spaced air inlet ducts 36 and 37 (FIGURE 3) for feeding air to the underside of the grate 1 (FIGURE 2) lead through the casing 19 and communicate with the annular chamber 18. The. chamber 18 is itself divided into two arcuate compartments 18A and 1813 by means of flaps 33A and 38B and baffles 39. Each compartment 18A and 183 communicates with several of the sections 16. The flap 38A is urged against the drum 3 by the pressure prevailing in the compartment 18A and the flap 38B is spring urged towards the drum 3 against the pressure prevailing in the compartment 18A. Both flaps 38A and 38B are pivotably mounted on the casing 19 and as will be described hereinafter the pressure in the compartment 18A exceeds that in the compartment 183.

At a location adjacent the chains 39, a vertical duct 49 extends upwardly from the space above the grate 1 and serves as an outlet for gases.

In use of the exchanger hot cement clinker falls down the shaft 23 from a kiln resting on a floor generally indicated at 41. The grate 1 is rotated by means of the motor 10 via the gearing 7/9 and the clinker which falls onto the grate 1 down the shaft 23 is carried through almost 360 to the scraper 24. Primary cooling air is supplied through the duct 37 and enters the compartment 18A from whence it passes to the underside of the firebars 4 and 5 by way of the apertures 17. The cooling air then passes upwardly through both the firebars 4 and 5 and the bed of clinker supported by the firehars, and is discharged mainly through the shaft 23 and into the kiln (not shown) but also through the duct 40. The flaps 38A, 38B and the bafiles 39 and the batiles substantially prevent the primary air from flowing circumferentially, the air being mainly confined to a 120 section of the grate 1. Similarly, secondary cooling air at a lower pressure than the primary air supplied to the duct 36 is supplied to the duct 37. This secondary air passes to the underside of the firebars 4 and 5' and subsequently passes up through the firebars 4 and 5 and the bed of clinker thereon to be exhausted mainly through the duct 4-0, but also partially through the shaft 23.

The clinker is carried through almost 360 by the grate 1 and is then scraped by the scraper 24 from the upper surface of the firebars 4 and 5, the clinker being directed onto the chute 26. Some clinker is carried under the scraper 24 which leaves about 1 inch of clinker on the grate 1, this layer of clinker serving to protect the firebars from mechanical damage and from damage due to overheating. The cooled clinker slides from the chute 26 onto the screen 27 and particles which are sufficiently small pass through the screen 27 and fall down the opening 31. The pieces of clinker which fail to pass through the screen 27 are hurled upwardly by the rotary hammer 28 and strike the plates 29 so that these larger pieces of clinker are broken and eventually become small enough to pass through the screen 27.

Clinker which falls through the firebars 4 and 5 is entrained by the scrapers 32 and carried along by the scrapers until the scrapers 32 reach the opening 35 whereupon the clinker is discharged down the opening 35 and is fed along with clinker falling down the opening 31 to the conveyor.

In use, the air discharged through the duct 40 may all be recirculated to the duct 36 or part of this air may be recirculated. In this case the cooling air is supplied via the duct 36 and passes upwardly through the section of the grate 1 which is connected with the compartment 18B. This air is then extracted via the duct 40 and all or part of this air reintroduced to the underside of the grate via the duct 37.

Such recirculated air passes upwardly through the section of the grate 1 connected with compartment 18A. After passing through the grate a second time the air is fed through duct 23 and into the kiln.

The configuration of the firebars 4 and 5 is such that only a small area of each firebar is exposed to the hot material whereas a relatively large area of the firebar is exposed to the cooling medium.

If desired the firebars 4 and 5 may be replaced by, or used in conjunction with, perforated plates and the grate 1 may be disc-like instead of annular.

The firebars are readily removable so that in the event that they become broken they can be replaced.

What is claimed is:

1. A heat exchanger comprising a housing, a rotatable annular grate mounted in said housing and constructed and arranged to support material in a granular or nodular form, a first scraper carried by said housing and arranged above and adjacent the grate for removing said material from the grate, means for passing gases through the grate and through the material thereon to effect heat exchange between the material and the gases while the material is being carried to the scraper by the rotating grate, portions of said housing defining an upwardly facing surface beneath said grate spaced from said grate for receiving material droppings from said grate, other portions of said housing defining an outlet opening in said surface, and a til second scraper carried by said grate and arranged beneath said grate and constructed and arranged to rotate with said grate adjacent said surface to displace said material droppings from said surface and into said outlet opening; a plurality of arcuately spaced generally radial baffles provided beneath the grate dividing the space beneath the grate into sections and constructed and arranged to inhibit flow of gases circumferentially of the grate beneath the grate; and further comprising at least two ducts arcuately spaced from each other around the grate, and drum means circumferentially bounding said sections and defining therebetween at least two compartments of arcuate form each communicating with respective of said at least two ducts, each compartment communicating with a plurality of said sections thereby communicating said at least two ducts with the space beneath the grate.

2. A heat exchanger according to claim 1, wherein said drum means comprises inner and outer rotatable drums supporting said grate, the outer drum being surrounded by a casing and the casing and the outer drum defining a chamber of annular form therebetween, said annular chamber being divided to form said compartments and the outer drum having apertures therein for placing said sections in communication with the compartments.

3. A heat exchanger according to claim 2 wherein said chamber is divided into compartments by flaps pivotally mounted on said casing and contacting said outer drum.

4. A heat exchanger comprising a housing, a rotatable annular grate mounted in said housing and constructed and arranged to support material in a granular or nodular form, a first scraper carried by said housing and arranged above and adjacent the grate for removing said material from the grate, means for passing gases through the grate and through the material thereon to effect heat exchange between the material and the gases while the material is being carried to the scraper by the rotating grate, portions of said housing defining an upwardly facing surface beneath said grate spaced from said grate for receiving material droppings from said grate, other portions of said housing defining an outlet opening in said surface, and a second scraper carried by said grate and arranged beneath said grate and constructed and arranged to rotate with said grate adjacent said surface to displace said material droppings from said surface and into said outlet opening; bafile means provided above the grate and dividing the space above the grate into sections for inhibiting flow of gases circun'iferentially of the grate above the grate; at least two ducts connected to the space beneath the grate and circumferentially spaced from each other around the grate, and conduit means connected to the space above the grate; said conduit means comprising first and second conduits, the first conduit communicating with a space to one side of said bafile means and the second conduit communicating with a space to the other side of said baffie means.

5. A heat exchanger according to claim 4 wherein one of said conduits serves as an inlet for the material.

References Cited by the Examiner UNITED STATES PATENTS 1,548,292 8/1925 Wedge -36 1,989,662 2/1935 Bernhard et al. 34--185 2,891,321 6/1959 Habel 34-174 3,168,384 2/1965 Greaves et al. 34168 FOREIGN PATENTS 506,260 5/1939 Great Britain.

KENNETH W. SPRAGUE, Primary Examiner. 

1. A HEAT EXCHANGER COMPRISING A HOUSING, A ROTATABLE ANNULAR GRATE MOUNTED IN SAID HOUSING AND CONSTRUCTED AND ARRANGED TO SUPPORT MATERIAL IN A GRANULAR OR NODULAR FORM, A FIRST SCRAPER CARRIED BY SAID HOUSING AND ARRANGED ABOVE AND ADJACENT THE GRATE FOR REMOVING SAID MATERIAL FROM THE GRATE, MEANS FOR PASSING GASES THROUGH THE GRATE AND THROUGH THE MATERIAL THEREON TO EFFECT HEAT EXCHANGE BETWEEN THE MATERIAL AND THE GASES WHILE THE MATERIAL IS BEING CARRIED TO THE SCRAPER BY THE ROTATING GRATE, PORTIONS OF SAID HOUSING DEFINING AN UPWARDLY FACING SURFACE BENEATH SAID GRATE SPACED FROM SAID GRATE FOR RECEIVING MATERIAL DROPPINGS FROM SAID GRATE, OTHER PORTIONS OF SAID HOUSING DEFINING AN OUTLET OPENING IN SAID SURFACE, AND A SECOND SCRAPER CARRIED BY SAID GRATE AND ARRANGED BENEATH SAID GRATE AND CONSTRUCTED AND ARRANGED TO ROTATE WITH 